Processing systems, such as plasma processing tools, rely on holding mechanisms to support a workpiece, such as a semiconductor, ceramic, or metal substrate or wafer, inside a process chamber during the performance of a treatment process. Certain holding mechanisms include a plurality of lift pins that are configured to raise or lower in unison for lifting and lowering the workpiece relative to a top surface of a support. In the lowered position, the tips of the lift pins are either flush with, or slightly recessed below, the top surface of the support so that the workpiece at least partially contacts the top surface. In the raised position, the tips of the lift pins contact a bottom surface (backside) of the workpiece and elevate the workpiece above the top surface of the support. Typically, multiple lift pins establish multiple points of contact with the backside of the workpiece. The resulting gap between the lifted workpiece and the surface of the support permits an access space for insertion of an end effector.
The requirement for lift pins in conventional processing systems necessitates one or more mechanical feedthroughs in the process chamber for transferring mechanical motion from a location outside of the process chamber to the lift pins. Each mechanical feedthrough requires at least one port extending through the chamber wall of the process chamber. Each port provides a prime location for vacuum leaks. Moreover, contact between the lift pins and the workpiece may damage or contaminate the backside of the workpiece. Further, the process of raising and lowering the lift pins may generate particles that contaminate the process chamber and, if not remediated, eventually, result in contamination of the processed workpieces.
It would therefore be desirable to provide a workpiece vertical lift mechanism that addresses these and other deficiencies or challenges of conventional processing systems.